Acta Diabetol (2006) 43:26–33 DOI 10.1007/s00592-006-0207-5 ORIGINAL
D.A. Arnall • A.G. Nelson • L. López • N. Sanz • L. Iversen • I. Sanz • L. Stambaugh • S.B. Arnall
The restorative effects of pulsed infrared light therapy on significant loss of peripheral protective sensation in patients with long-term type 1 and type 2 diabetes mellitus Received: 23 August 2005 / Accepted in revised form: 5 December 2005
Abstract Pulsed infrared light therapy (PILT) has been shown to increase peripheral sensation in diabetic patients with diabetic peripheral neuropathy (DPN). However, most studies last for very short periods, with the subjects receiving only 6–20 treatments. The purpose of this study was to evaluate the effectiveness of an eight-week course
D.A. Arnall () Physical Therapy Department East Tennessee State University Box 70624, Johnson City, TN 37614, USA E-mail:
[email protected] A.G. Nelson Department of Kinesiology Louisiana State University Baton Rouge, USA L. López • N. Sanz University of Valencia Department of Physiotherapy Valencia, Spain L. Iversen University of Copenhagen Panum Institute, Denmark I. Sanz Clinical Hospital University of Valencia Valencia, Spain L. Stambaugh GE Analytical Instruments Boulder, CO, USA S.B. Arnall Jonesborough, TN, USA
of PILT in reversing long-standing, profound DPN in patients with type 1 and type 2 diabetes. Twenty-two subjects with a diagnosis of type 1 (n=2) or type 2 (n=20) diabetes participated in the study. PILT was administered to one foot chosen at random with the other foot serving as a within-subject control (no treatment). Patients underwent 24 treatments (3 times/week, for eight weeks) for 30 min per treatment. Changes in peripheral protective sensation (PPS) were measured using Semmes-Weinstein monofilaments (SWM) ranging from 3.7 to 6.48. PILT improved PPS even in patients with long-standing chronic neuropathies whose initial pre-study sensation was not measurable with a 200-g SWM. PILT significantly improves PPS. While the exact mechanism of action is not understood, infrared light may improve peripheral neuropathies by improving foot perfusion by stimulating nitric oxide production. Key words Pulsed infrared light therapy • Peripheral neuropathy • Peripheral protective sensation • Loss of protective sensation • Type 1 diabetes mellitus • Type 2 diabetes mellitus • Semmes-Weinstein monofilaments • Infrared light modality • Physical therapy
Introduction Patients with diabetes have many pathological complications that accompany the physiological impairment of either making no insulin (type 1), or developing peripheral resistance to insulin (type 2). In either type of diabetes, the derangement of the normal insulin-to-glucose relationship makes the maintenance of euglycaemia an hourto-hour challenge. Hypoglycaemia and hyperglycaemia are an ever-present reality in the lives of these patients. Poor control over hyperglycaemia brings with it a plethora of chronic, debilitating conditions such as neuropathic
D.A. Arnall et al.: PILT improves peripheral protective sensation
ulcers, peripheral vascular disease, atherosclerosis, hypertension, neuropathies, nephropathies, immune system deficiencies and compromised wound healing. Significant pharmacological interventions in the last 20 years have been helpful in assisting patients with diabetes to gain some control over hyperglycaemia. The development of ACE inhibitors, hypoglycaemic agents and long-acting insulins have been encouraging. However, hyperglycaemia, and its attendant pathological effects on organ systems, remains a chief medical concern. Recently a new treatment, pulsed infrared light therapy (PILT), has become available. PILT represents a breakthrough as a non-pharmacological and non-invasive therapy for the treatment of neuropathies and the consequent loss of peripheral protective sensation (PPS). PILT gives patients with diabetes a hope that the loss of PPS may be prevented or reversed as long as afferent nerves in the feet and legs have not permanently stopped functioning. A recent study by Kochman et al. [1] suggests that losses in PPS can be reversed. The authors used infrared light therapy on both type 1 (n=25) and type 2 (n=24) diabetics, who had been diagnosed with peripheral neuropathies. Treatments consisted of twelve 30-min treatments spread over 30 days. Semmes-Weinstein monofilaments (SWM) (size range: 3.22–6.45) determined the patient’s improvement in PPS at three sites: great toe, fourth toe, plantar arch. After the treatments, the authors reported 100% of the patients had SWM values below 5.07 (the 10-g force monofilament commonly used in foot-screening clinics signaling the beginning of loss of protective sensation (LOPS) [2]). Their findings indicated a normal or near normal attainment of PPS, suggesting that infrared light therapy was successful in acutely reversing the loss of PPS in all subjects. Unfortunately, this study was not controlled or blinded. Additionally, the authors did not provide any clear information concerning site-specific changes due to the experimental treatment. In a similar study, Leonard et al. [3] studied two different diabetic groups – group 1 (n=18), with an insensitivity to the 5.07 monofilament (mild to moderate LOPS); and group 2 (n=9), with a profound insensitivity to the 6.65 monofilament (severe LOPS). After testing sensitivity to the 5.07 monofilament at five separate sites, each group received 40 min of PILT, three times/week for two weeks (six total treatments) on the experimental foot and an equal number of sham treatments on the control foot. The authors reported that, after the six treatments, the number of sites sensitive to the 5.07 monofilament improved in group 1’s treated foot, with no improvement in the sham-treated foot. The authors then changed the control vs. experimental design of their study by giving an additional six treatments of PILT to both the former sham feet and the experimental feet. When both feet received PILT during the second two-week period, the number of sites sensitive to monofilament testing improved in both
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feet. However, this study was unclear as to whether the patients ever achieved restoration of normal sensation i.e., were the patients able to sense a monofilament lower than the 5.07 SWM. Additionally, the authors reported that the sensitivity to the 5.07 SWM in group 2 – the more severely involved patients – did not change after either the first six treatments or the second six treatments. Sadly, the authors could not report any changes in sensitivity from the 6.65 SWM down to lower monofilaments, as they did not use any SWMs between 6.65 and 5.07. Finally, no site-specific response to PILT was reported. In another study by Kochman [4], patients with a positive loss of PPS as determined with negative sensibility to the 5.07 SWM, a positive history of self-reported falls in a 3-month period, and a suspected diminution of postural balance as suggested by a fall history, were treated with PILT. Depending on their degree of LOPS, 38 patients received PILT for 30–40 min, for 6–20 (average 12) treatments. In addition, all patients participated in a balance training programme. Kochman [4] reported that all subjects had a complete restoration of PPS and that their history of falling improved to fewer falls per month with an improved Tinetti balance score. Unfortunately, this study gathered its data from a retrospective chart review design and, therefore, had no controls. Additionally, there was no accurate history available for the number of falls, making the central thesis of improved balance secondary to improved PPS as a result of PILT difficult to substantiate. Finally, it was difficult to attribute the changes in the patient’s PPS to either PILT, the balance retraining that the patients received or any pharmacological intervention the patients may have received. Finally, Prendergast et al. [5] reported that 27 patients received 10 PILT treatments each lasting 40 min over a 2week period. These authors assessed peripheral sensibility in the feet using a Neurometer CPT (current perception threshold) diagnostic tool. After 10 PILT treatments, the authors stated that most of the patients had some level of increased sensibility in their feet. However, from the data provided, it is difficult to relate the CPT measures of improved PPS to improvements measured by the more commonly employed SWM. In summary, there is a paucity of uniformly well designed studies providing convincing evidence that the application of PILT to diabetic patients with a loss of PPS can totally restore PPS to normal values. Additionally, most studies have based their argument that PILT improves PPS after finding a positive SWM score in only one of several sites tested. The site-specific efficacy of PILT, however, has not been reported. Moreover, there have been no controlled trials published where patients with long-term severe losses of PPS have regained normal PPS after the application of PILT. This does not imply that PILT is ineffectual for the long-term patient. Instead, it suggests that studies with a greater number of treatments
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D.A. Arnall et al.: PILT improves peripheral protective sensation
that specifically evaluate several sites are needed. Therefore, the purpose of this study is to determine if the application of eight weeks of PILT improves site-specific PPS in patients with a chronic history of type 1 and type 2 diabetes who have sustained severe losses in PPS.
Methods
All subjects were interviewed concerning their medical history. Pertinent patient information consisted of: (a) years living with diabetes; (b) height, weight and body mass index (BMI); (c) current medication inventory; (d) most recent available glycosylated haemoglobin (HbA1c); (e) history of a nephropathy or a retinopathy since diabetes diagnosis; (f) a standard cardiovascular risk profile evaluating hypercholesterolaemia, hypertriglyceridaemia, hypertension, smoking history and physical activity level. A summary of the anthropomorphic characteristics and other pertinent subject information is contained in Table 1.
Subjects This study was reviewed and approved by the Comité Ético of the Hospital Clínico de Valencia, Valencia, España prior to the recruitment of subjects and the gathering of data. Twenty-two patients with a clinical diagnosis of type 1 (n=2) or type 2 (n=20) diabetes mellitus participated in this study. The subjects for this study were recruited from the Asociacíon de Diabetes of Valencia, España who lived in Valencia or in the semiautonomous region of the Province of Valencia. Subject exclusion criteria for this study included: (a) no open wounds in either lower extremity; (b) a normal haematocrit which was between 30% and 50%; (c) a normal haemoglobin which was between 9 and 18 g/dl; (d) the patient was not in acute renal failure. No attempt was made to change physician-directed pharmacological interventions that patients were receiving when they entered the study. The research staff provided the patients with information concerning the benefits and risks associated with their participation in the study after which the prospective subjects signed a consent form and entered the study.
Tests and measurements Body mass index BMI (kg/m2) was measured at the beginning of the study. A BMI
